1. Field of the Invention
The present invention relates to rotary actuators that output driving torque as a result of output shafts pivoting in a rotational direction due to action of a pressure medium.
2. Description of the Related Art
A rotary actuator having such a configuration as the one disclosed in U.S. Pat. No. 5,601,165 is known as one of the rotary actuators that output driving torque as a result of an output shaft pivoting in a rotational direction due to action of a pressure fluid serving as a pressure medium.
In the rotary actuator disclosed in U.S. Pat. No. 5,601,165, ribs are provided within a cylinder as an integral unit, and vanes are provided to an output shaft rotatably installed within the cylinder. Both ends of the cylinder are provided with end caps. The ribs and the inner wall surface of the cylinder, as well as the vanes and the outer wall surface of the output shaft form pressure chambers. Adjoining pressure chambers are alternatively supplied with a pressure fluid, the output shaft thereby pivots in a rotational direction due to action of the pressure fluid, and, as a result, driving torque is output.
In the above rotary actuator, seals are inserted into grooves provided on the ribs and the vanes. The seals inserted into the ribs are pressed against the outer wall surface of the output shaft, and the seals inserted into the vanes are pressed against the inner wall surface of the cylinder. Thus the adjoining pressure chambers are sealed against each other. The pressure chambers are also sealed against each other by means of gaskets between the end caps and the output shaft, as well as between the end caps and the vanes.